1. Field of the Invention
This invention relates in general to the cold rolling of metal strip. More specifically, it relates to a system for controlling the thickness and camber (straightness) of the strip product. In another aspect, the invention provides a roll stand frame wherein one roll drive motor is mounted on a pivoting door to allow for access to the rolls and interior of the roll frame.
2. The Prior Art
The prior art uses the term "camber" to defime the amount of edge curvature of a strip width of rolled sheet metal with reference to a straight edge. The prior art discloses a number of devices for effecting control of the strip "camber". Typically, these prior art systems change the shape of one of the metal working rolls, by changing the temperature profile of that roll, responsive to signals received from a sensing element which monitors the strip product. U.S. Pat. No. 4,262,511 issued to Boisvert et al, for example, discloses a "shapemeter" in the form of a segmented rotor supported by an air cushion and in contact with the sheet metal product. Pneumatic signals from the segmented rotor are converted into electrical signals which, in turn, control the distribution of coolant onto the metal roll surfaces. The teachings of U.S. Pat. No. 3,499,306 issued to Pearson are somewhat similar.
Control of the gauge or thickness of rolled sheet metal has been of major concern in the art since the inception of metal rolling and the approaches to such control have been quite varied. Typically, provision is made for measurement of the force tending to separate the metal working rolls and for regulation of that force by adjustment of the position of one roll with respect to the other. See, for example, U.S. Pat. No. 3,550,413 issued to Barnikel. However, where the thickness of the feed stock varies, regulation of the roll separating force alone is insufficient to produce a product of constant thickness or gauge. With this latter problem in mind Fox, in U.S. Pat. No. 3,391,557 proposed to monitor the thickness of the metal feedstock and to vary the loading on the millstand roll journals in accordance with variations in the thickness of the feed stock. Additionally, numerous other approaches have been attempted. For example, Reinhardt et al U.S. Pat. No. 3,389,588 discloses an electrical system for measuring the actual roll gap and for operating a hydraulic system for raising or lowering the bottom work roll to maintain the desired roll gap. Wallace U.S. Pat. No. 3,103,138 measures the actual thickness of the strip product by an x-ray device and varies the hydraulic pressure exerted on the upper working roll responsive to a signal generated by the X-ray device.
An ancillary problem in the metal rolling industry is the removal and replacement of the cylindrical rolls and bearings. Mersek in U.S. Pat. No. 3,323,344 discloses an arrangement wherein the outboard bearing housing for the metal rolls is constructed and arranged for pivotal movement to a position permitting changing of the roll dies.
It is an object of the present invention to provide a metal rolling mill, especially a cold rolling mill, which provides a rolled product of uniform thickness (gauge) and straightness (camber), even with a feedstock strip of somewhat variable thickness.
It is another object of the present invention to provide a control system whereby gauge and camber may be regulated with insignificant lag time between detection and correction.
Another object of the present invention is to provide a control system for tandem control of such roll millstands to regulate the strip tension between the roll millstands.
Yet another object of the present invention is to provide a simple, relatively maintenance-free device for measurement of changes in the actual roll gap.
Still another object of the present invention is to provide a roll millstand in which adjustments to the cross-sectional profile of the strip may be made simply by adjusting the tilt of one metal working roll with respect to the other, and without any change in the shape of the rolls per se.
A still further object of the invention is provision of a frame for the roll millstand permitting access for changing the cylindrical rolls.
A further object is to create a very compact and moderate-cost millstand with relatively high torque and horsepower per unit width.
Other objects and further scope of applicability of the present invention will become apparent from a reading of the detailed description to follow, taken in conjunction with the accompanying drawings.